EDUCATIONAL LOGGING REQUIREMENTS
In order to substantiate your visit and comply with the educational requirement for Earth Caches you have to submit your answers to the following questions to the cache developers via their profile:
For purposes of logging this cache you must answer the following three questions.
1) Is the rock out of which the statue is made Foliated or Non-Foliated?
2) What is the name of this rock? Explain how you arrived at this conclusion by describing your route through the table.
3) When facing the stature there is a large defect on the bottom right of the steps. Is this a natural defect or physical (mechanical) damage that has been repaired?
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You are standing by a statute of Queen Victoria. Victoria was the monarch of the United Kingdom of Great Britain and Ireland from 20 June 1837 until her death in 1901 but on this occasion we are not interested in the lady but the material of the statue and the plinth and the metamorphic rock it is made of.
Metamorphic rocks are rocks that have undergone a change from their original form due to changes in temperature, pressure or chemical alteration. The classification of metamorphic rocks is based on the minerals that are present and the temperature and pressure at which these minerals form. A simplified system for the identification of this rock is used and is based on its texture and composition.
Texture Texture is divided into two groups. Foliated textures show a distinct planar character. This means that the minerals in the rock are all aligned with each other. This planar character can be flat like a piece of slate or folded. Non-foliated textures have minerals that are not aligned. Essentially, the minerals are randomly oriented.
Foliation Foliated textures show four types of foliation. Slaty cleavage is composed of platy minerals that are too small to see. Typically, these rocks split along parallel, planar surfaces. Phyllitic foliation is composed of platy minerals that are slightly larger than those found in slaty cleavage, but generally are still too small to see with the unaided eye. The larger size gives the foliation a slighly shiny appearance. Schistose foliation is composed of larger minerals which are visible to the unaided eye. Platy minerals tend to dominate. Gneissic banding is the easiest of the foliations to recognize. It is composed of alternating bands of dark and light minerals.
Non-Foliation Non-foliated textures are identified by their lack of planar character. Further identification of non-foliated rocks is dependent on the composition of the minerals or components in the rock. Anthracite coal is similar to bituminous coal. Both are black in colour , and is composed of carbon. Anthracite coal is generally shiny in appearance and breaks with a conchoidal fracture (broken glass also shows this type of fracture). Metaconglomerate is composed of pebbles and gravel that have been flattened due to directed pressure. Quartzite is composed of quartz sand grains. Quartz has a hardness of 7, which makes it difficult to scratch. Marble is composed of calcite and will readily react to a small drop of HCl.
The table used for the identification of metamorphic rock is set out below.
| METAMORPHIC ROCK IDENTIFICATION CHART |
| TEXTURE |
FOLIATION |
COMPOSITION |
TYPE |
PARENT ROCK |
ROCK NAME |
| Foliated |
slaty |
mica |
Regional |
Mudstone |
Slate |
| phyllitic |
quartz, mica, chlorite |
Regional |
Mudstone |
Phyllite |
| schistose |
mica, quartz |
Regional |
Slate |
Schist |
| schistose |
amphibole, plagioclase |
Regional |
Basalt or Gabbro |
Amphibolite |
| gneissic banding |
feldspar, mica, quartz |
Regional |
Schist |
Gneiss |
| Non-Foliated |
|
carbon |
Contact or Regional |
Bituminous Coal |
Anthracite Coal |
|
quartz, rock fragments |
Contact or Regional |
Conglomerate |
Metaconglomerate |
|
calcite |
Contact or Regional |
Limestone |
Marble |
|
quartz |
Contact or Regional |
Sandstone |
Quartzite |
Acknowledgements
Picture FireflyAfrica
Table Earth Science Lab This site has a number of examples to test rock identification